The engine immobiliser system is designed to prevent the vehicle from being stolen. This system uses a transponder key ecu that stores the key codes of authorized ignition keys. If an attempt is made to start the engine using an unauthorized key, the ecu sends a signal to the ecm to prohibit fuel delivery and ignition, effectively disabling the engine.

The transponder key coil receives this signal, the transponder key amplifier amplifies it, and then the signal is transmitted to the ecu. The ecu matches the key's id code with the vehicle's id code, which was previously registered in the ecu and then communicates the results to the ecm using sfi communication.
Engine immobiliser system
How to proceed with troubleshootingHow to proceed with troubleshooting
Hint:
*: Use the intelligent tester.
Hint:
If the display indicates a communication fault in the tester,
inspect the dlc3.
Hint:
Record or print dtcs and freeze frame data, if necessary.
Hint:
If the engine does not start, first perform the "check dtc"
procedures a ...
Transmission fluid temperature sensor "A" circuit
Description
The automatic transmission fluid (atf) temperature sensor converts the atf
temperature into a
resistance value which is input into the ecm.
The ecm applies a voltage to the temperature sensor through ecm terminal tho1.
The sensor resistance changes with the atf temperature. ...
Removal
Disconnect cable from negative battery terminal
Caution:
Wait at least 90 seconds after disconnecting the
cable from the negative (-) battery terminal to
prevent airbag and seat belt pretensioner activation.
Remove mass air flow meter
Disconnect the mass air flow meter connector.
...